Broadband wireless is expected to be one of the main drivers of the telecommunications industry. There is a substantial increase in demand for broadband connectivity, with personal broadband being the key growth engine for mobile wireless broadband networks.
In conventional wireless telecommunications networks, network planning, deployment and interference management of base stations are programmed in advance at the time of installation by an operator. The traditional approach for mobile WiMAX network infrastructure deployment is similar to that of cellular phone networks. The network is based on macro-cell deployment, that is, the base stations, radios and antennas are installed on top of high towers, transmitting at high power, so as to maximize the base station coverage area. However, as smaller and smaller cells are utilized, the increasing numbers of base stations, particularly femtocells, in a geographical area create a major problem of interference management.
There is known from applicants' co-pending US patent application publication no. US 2008/0090575, entitled WiMAX Access Point Network with Backhaul Technology, a mobile WiMAX system, as defined in IEEE Standard 802.16e-2005 Standardization for WiMAX. According to this application, there is provided in-band, point-to-point backhaul between the various network access elements in a WiMAX network deployed in micro- or pico-cells. This WiMAX network provides increased traffic capacity of the base station, while not greatly increasing the interference caused with neighboring cells, preferably by using several directional antennae on each base station, and utilizing MIMO or Beam forming (spatial filtering) techniques to reduce interference. This patent application also describes in detail the self planning capabilities of base stations organized in a virtual cluster with a central feeder, where there is communication via point to point backhaul between the base stations in each cluster.
However, as the number of femtocells deployed in indoor locations increases, network planning (i.e., allocation of radio resources, frequency, power, and sector ID to each femtocell) becomes another major problem. Since femtocells (base stations) now sit in the end user premises, it is unreasonable to request the user to configure the femtocell by himself. Accordingly, a simple way to synchronize his femtocell to neighboring femtocells, both indoors and outdoors, is required.
Furthermore, in the past, only the mobile stations were required to synchronize on their associated base stations, due to the physical separation between base stations. Nowadays, the various base stations must also synchronize on each other, in order for a mobile wireless network to operate properly. The quality of synchronization in the network directly impacts the interference generated by the network. The transmission of voice, video and data through any communication network requires a stable frequency reference, and precise frequency synchronization is especially critical in mobile networks for the successful call signal hand-off between base stations, as well as for the transport of real-time services.
Accordingly, with the movement of base stations indoors, and as more networks transition to an IP-centric backhaul, there is a need for a method and device for providing synchronization between neighboring base stations and interference management in micro-, pico- and femtocell base stations.